Recovering an old Photoshop version from 2010 without a serial number

I have upgraded my operating software to Windows 8.1 which promptly deleted, among other programs, my Photoshop CS5. I would like to recover my old version but am unable to do so because my version was registered through JourneyEd, an educational company. JourneyEd has no record of my serial number or my last name or the product number (the only thing I have and the box packaging). I cannot reinstall without the serial number. Do you have any suggestions what would be my next step? I could upgrade to the latest version of Photoshop but I do not want to buy a whole new Photoshop as my old one is still adequate for my needs. Thank you for your suggestions.